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DNS DDoS Attack Takes Down China Internet

The latest news is a few million Chinese Internet users had trouble accessing any websites yesterday due to a DDoS attack on the DNS system from one of the countries registrars.

It just shows that China has an inherently weak infrastructure if such a large portion of people can be disrupted with an attack to a single location.

I guess the users haven’t heard of OpenDNS either, or perhaps they can’t use it because it’s blocked by the ‘Great Firewall of China‘.

An attack on the servers of a domain registrar in China caused an online video application to cripple Internet access in parts of the country late on Wednesday.

Internet access was affected in five northern and coastal provinces after the DNS (domain name system) attack, which targeted just one company but caused unanswered information requests to flood China’s telecommunications networks, China’s IT ministry said in a statement on its Web site. The DNS is what computers use to find each other on the Internet.

The incident revealed holes in China’s DNS that are “very strange” for such a big country, said Konstantin Sapronov, head of Kaspersky’s Virus Lab in China.

The problems started when registrar DNSPod’s DNS servers were targeted with a DDOS (distributed denial of service) attack, described by the company in an online statement. In such an attack, the attacker orders a legion of compromised computers to try to communicate with a server all at once, which overwhelms the server and crushes its ability to return requests for information.

A DoS attack on the root domain servers of any organisation is always one of the most effective as you don’t have to saturate a large pipe, you just have to make the machine max out it’s CPU/RAM so it can’t serve any more requests.

It’s much better than trying to take a corporate network offline by filling up their main line. Targeted attacks are always the most effecient.

Internet access returned to normal in the late night several hours later, according to the government statement.

China had almost 300 million Internet users at the end of last year, according to the country’s domain registry agency, and streaming online video is as popular among young people as it is in Western countries.

The event, the first of its kind in China, suggests the country needs to improve its rules managing the DNS, said Zhao Wei, CEO of Knownsec, a Beijing security firm.

The original attack transformed into a regional DNS jam essentially because Baofeng is so popular, said Zhao.

Such programs may need smarter code, which could instruct them to withdraw DNS requests that go unanswered, he said. The way unanswered requests are redirected to higher-level servers could also be changed, Zhao said.

An interesting point is that the registrar that was attacked hosted the DNS for the very popular video streaming site Baofeng – the traffic was so high for this site that that unanswered DNS requests turned into another traffic jam having the effective of multiplying the original DDoS attack.

I’m guessing this was an unintended side effect, but it worked out well for the attackers.